The prior art has lacked many features defined in the objectives of this invention as set forth herebelow.
An important object of the invention is to provide a pneumatic circuit, capable of controlling the conveyor and the strapper in a manner so as to apply at least one strap on to an object at a desired location with respect to an end of the object, and which is controllable by one single contact control, so that the position of the forward end of the object moving through the machine determines automatically the position of a first strap, the same pre-set programmed distance from forward end of an object to strap position being repeated automatically on subsequent objects moving through the machine.
Another objective is to provide an air circuit as described which can be changed so as to space the first strap a different preselected distance from a forward end of an object moving through.
A further object is to provide an air circuit capable of controlling automatically the placement of a second strap on an object, responsive to the passing of the rearward end of the object past a given point on the machine so that even if an object is ten feet long, while the previous object was only one foot long, nevertheless, the ten foot object will receive its rear end strap the same preselected distance from the rearward end of the ten foot object as was rearward end strap spacing from the end of the previous one foot object.
Still another objective is to provide for the use of the same upward and downward moving trigger for downward movement as the forward end of an object depresses the trigger initiating the first strap cycle and upward movement of the same trigger as the rearward end of the object passes, thereby releasing the spring biased trigger to move upward, thereby initiating the rearward end strap cycle.
Another object of the invention is to provide an air circuit for control of such a machine which as a time lapse for the application of the first strap after the pressure of the trigger by the front of an object being adjustable independently of adjustment of the time lapse between passage of the rearward end of the object past the same control trigger and the application of the second strap. In this way the invention provides for the placing of a first strap at one distance from the forward end of an object and the placing of the last strap on the object at a different distance if desired from the rearward end of the object.
A still further object is to provide an air circuit mechanism for initiating a third strap intermediate the front and rear straps on an ojbect, the third and intermediate strapping cycle being initiated by the simultaneous depression of the trigger used for initiating the application of the front strap, and a second trigger disposed rearwardly on the machine with regard to object directional motion, the second trigger being called the intermediate strap trigger. Such simultaneous depression of the second or intermediate strap trigger and the first or front strap initiating trigger in effect calling upon the air circuitry to realize that the object is long enough to depress both triggers and, therefore, the object is in need of at least one intermediate strap disposed between the front and rear straps on the object. The number of intermediate straps being pre-set by two factors, the first factor being a setting of just how far apart straps shall be placed with respect to a previous strap. A second factor being the length of the object itself, whereby the intermediate strapping initiation circuit places one or more straps on the object proportional to how many units of distance there are in its length when one unit of distance is considered to be the distance between intermediate straps.
Still another object is to provide an intermediate strapping initiation air circuitry which will place the first of the intermediate straps at a variable pre-set distance behind the front strap of the object.
A further object is to provide an air circuit for such a machine which is capable of being set so that no strapping cycles are automatically triggered, but instead so that the only straps to be placed on an object are one or more straps placed in response to a manual triggering.
A still further object is to provide air circuitry for initiating the application of the front strap on an object by means of depressing a first trigger which opens a four-way valve so as to cause air from a general air source to flow through a first flow control freely to a cylinder on one side of its piston for causing the piston to move gradually toward a position for piston actuation of front strapping on the object, the speed of motion of the piston being regulated by a flow control in a line leading from the other side of the piston to atmospheric exhaust, the timing of the second mentioned flow control determining the time between first triggering by the object and application of the first strap, the completion of movement of the plunger in a first direction resultant from the first triggering to a trip point at which a first belt stop initiation valve is actuated.